Irritating noises, including outside speech, oftentimes is problematic in a wide range of settings including, for example, offices, homes, libraries, and/or the like. Interestingly, people tend to tolerate the noises that they themselves make, even though they sometimes are unaware of the trouble that they are making for others.
In fact, there are many known potential adverse effects elicited by enduring annoying sounds. These adverse effects can range from productivity losses for organizations (e.g., for failure to maintain and/or interruptions in concentration) to medical issues for people (e.g., the onset of headaches caused by annoying sounds, irritability, increased heart rate, and/or the like) and to even the urge to seek a new work environment. Misophonia, a learned condition relating to the association of sound with something unpleasant, also happens from time-to-time. Some people suffer from acoustic hyper-vigilance or oversensitivity to certain sounds.
In many settings, sound annoyance oftentimes is related to loudness, abruptness, high pitch and, in case of speech sounds, the speech content. In many cases, there are certain components in speech or noise that make them particularly disruptive or irritating. With respect to speech content, humans tend to strain to hear what is said, which has been found to subconsciously add to the annoyance. That is, once one is aware of somebody speaking, one oftentimes becomes involuntarily involved, adding a sort of subconscious annoyance.
People oftentimes are irritated by high frequencies (e.g., sounds in the 2,000-4,000 Hz range). These sounds do not need to be of high intensity to be perceived to be loud. In this regard, FIG. 1 is a graph showing perceived human hearing at a constant level, plotting sound pressure level against frequency. As can be seen, the “equal loudness sound curve” in FIG. 1 demonstrates that lower-frequency sounds with high sound pressure levels generally are perceived the same way that higher-frequency sounds with lower sound pressure levels are perceived. Typically, irritation increases with volume of the noise.
Sound waves propagate primarily in a longitudinal way, by alternating compressions and rarefactions of air. When the waves hit a wall, the distortion of molecules creates pressure on the outside of the wall that, in turn, emanates secondary sound.
It will be appreciated that it would be desirable to design a wall with noise-cancellation properties. Generally, the more porous a material is and the greater its thickness, the more soundproof it is. Glass is a good sound reflector but unfortunately is not a good sound insulator. Thus, it will be appreciated that it would be desirable to design a transparent wall with noise-cancellation properties.
Sound-insulating windows have been known in the art. One mainstream approach involves increasing the Sound Transmission Class (STC) of the wall. STC is an integer rating of how well a wall attenuates sound. It is weighted over 16 frequencies across the range of human hearing. STC can be increased by, for example, using of certain geometry of double-pane glass walls in order to destructively resonate sound; increasing the STC of single- or double-pane walls by increasing thickness of the glass, and/or using laminated glass.
Unfortunately, however, these techniques come at a cost. For example, increasing the thickness of single-pane glass allows only modest sound abatement, while adding to the cost. The use of double-pane glass, albeit more effective, typically requires the use of at least two comparatively thick (e.g., 6-12.5 mm) glass sheets. These approaches also typically require high tolerances in the wall construction, and the use of special pliant mechanical connections in order to avoid flanking effects. Glass of such thickness is heavy and expensive, and results in a high installation cost.
Furthermore, double-pane walls typically work well primarily for low-frequency sounds. This can limit their effectiveness to a smaller number of applications such as, for example, to exterior walls to counteract the low-frequency noise of jet and car engines, noise of seaports, railways, etc. At the same time, most speech sounds responsible for both annoyance and speech recognition lye within the 1800-2400 Hz range. It therefore would be desirable to achieve noise cancellation in this higher-frequency range, e.g., in order to help block irritating components and increase speech privacy.
Instead of abating higher-frequency noise, some solutions focus on sound masking. For instance, sounds of various frequencies may be electronically overlapped through a speaker, so that the extra sound is provided “on top of” the original noise. This approach obscures the irritation, but it unfortunately also creates additional noise, which some people perceive as irritating in itself.
Still another approach for achieving noise cancellation is used in Bose headphones, for example. This approach involves registering incoming noise and creating a counteracting noise that is out of phase with the registered incoming noise. One difficulty of this concept for walls, however, is that it typically only works well on a small area and it suitable primarily for continuous sounds (such as, for example, the hum of engines).
Thus, it will be appreciated that it would be desirable to provide for techniques that overcome some or all of the above-described and/or other problems. For example, it will be appreciated that it would be desirable to provide acoustic walls that help reduce or otherwise compensate for sounds that cause irritation and annoyance to users.
One aspect of certain example embodiments relates to an acoustic wall assembly that helps overcome some or all of the above-described and/or other problems.
Another aspect of certain example embodiments relates to an optically transparent interior glass wall assembly with a low STC.
Yet another aspect of certain example embodiments relates to improving the acoustics of rooms formed by and/or contained within the example wall assemblies disclosed herein. Acoustics of the room advantageously can be improved by, for example, increasing speech privacy, obscuring irritating outside noises otherwise perceivable in the room, providing counter-surveillance properties, and/or the like.
In certain example embodiments, an acoustic wall assembly is provided. Inner and outer walls are substantially parallel to one another, with a gap being defined therebetween. At least one set of openings is formed in the inner and/or outer wall(s), with the at least one set of openings being configured to generate reverberation that masks sound waves incident on the wall(s) in which the at least one set of openings is/are formed.
In certain example embodiments, an acoustic wall assembly is provided. Inner and outer walls are substantially parallel to one another, with a gap being defined therebetween. At least one set of reverberation-generating elements is sized, shaped, and arranged in the inner and/or outer walls to selectively generate pressure waves in the gap to disrupt, via a reverberative effect, noise in a predetermined frequency range that otherwise would pass through the acoustic wall assembly.
In certain example embodiments, a method of making a sound-masking wall assembly is provided. Inner and outer walls are substantially parallel to one another, with a gap being defined therebetween. At least one set of reverberation-generating elements that is sized, shaped, and arranged in the inner and/or outer walls in which they are formed to selectively generate pressure waves in the gap to disrupt, via a reverberative effect, noise in a predetermined frequency range that otherwise would pass through the acoustic wall assembly.
The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.